1. Field of the Invention
The present invention relates to snow plows, and more particularly to a snow plow wing attachment.
2. Description of the Prior Art
Present day wing blades on snow plows are usually mounted at their front end to a slider device on a frame mounted to the side of a cab of a vehicle, while the rear of the wing blade is held by pivotally connected support arms with means for lifting the end of the blade and drawing it more closely to the cab of the vehicle when the wing blade is not in use. The means for lifting and drawing in the end of the wing blade to the cab vehicle is conventionally based on a system of pulleys and cables, as illustrated in U.S. Pat. Nos. 2,632,262, Whittey, 1953; 2,193,532, Frink, 1940; and 3,125,818, Kraft et al, 1964; and Canadian Pat. No. 609,002, Obst, 1960.
More recently, attempts have been made to eliminate the use of cables and overhanging frames so as to simplify the construction of the apparatus required for a wing blade on a snow plow. Such examples are shown in U.S. Pat. Nos. 4,045,892, Farrell, 1977; and 4,096,652, Raines et al, 1978. In the Farrell patent, mere front and rear posts are provided on which sliders are mounted and hydraulically controlled, while an additional hydraulic cylinder arm is provided between the support arms for moving the side wing upwardly and closer to the cab in the case of non-use of the wing blade. In the case of the Raines et al patent, there are no posts to support the rear of the snow plow, but the support members are merely pivoted to a support member mounted to the frame of the vehicle while the front of the blade is adapted to travel vertically on the basis of the cable and pulley system. It has been found, however, that with the evolution of hydraulic components in the control and support of the wing blade, more arms are required to control the end of the wing tip as shown in the Raines et al and Farrell patents, and the proliferation of these arms in some constructions has the disadvantage of the arms being constrained one against the other from moving the plow into an intimate proximity to the cab of the vehicle. Further, it has been found in the utilization of hydraulic cylinders and rigid support members that the wing tip is less subject to vertical play when in use, that is, when the lower scraping edge of the plow or wing blade meets a small bump or other obstacle, the wing blade has less of a possibility of moving upwardly and over such a bump which might be found in the road bed since it is being held in a triangle of arms which hold the plow in an almost fixed condition. Furthermore, it is still found that as in the Farrell patent, the posts must be made considerably higher than would be desirable since it must be high enough to contain the full piston and cylinder arrangement controlling the slide of the support member arms especially when the hydraulic cylinder and piston is being telescoped to move the slide upwardly. The posts must be high enough to give the slide sufficient travel.